The kth percentile is a value in a data set that splits the data into two pieces: If lower piece contains k percent of the data, then upper piece contains the rest of the data means (100 – k) percent, because the total amount of data percentage is 100% where k is any number between 0 and 100 & median will the 50th percentile.
1. First of all arrange all values from smallest to largest.
2. Mulitiply the 90 percent with total number of data if multiplied product is not whole number, round them.
3. Rounding number will be the test data.(Smallest to largest) suppose it is 5
4. Then you go until you find the 5th value in the data set . This value will be 90th percentile. Lets take an example ,suppose 4 days soaked CBR for 10 test in percentage is 15.86,10.32,19.08,11.87,23.84,18.73,16.74,18.15,17.27 & 19.32
then simplified solution can be determined as below :
step 1. First arrange with smallest to largest value it will be
10.32, 11.87, 15.86, 16.74,17.27,18.15,18.73,19.08,19.32,23.84
Step 2. Multiply 10 by 90% i.e 10 x .09 = 9
Step 3. Counting from left to right (from the smallest to the largest value in the above CBR set), you go until you find the 9th value in the step 2 data sheet & this value is 19.32, and it’s the 90th percentile for this data set.